Thermostat



March 5, 1929. 1 A, M PHELAN 1,704,370

THERMOSTAT Filed Sept. 22, 192,4 '3 SheetsJ-:She t l i9 6, a@

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L. A. M. PHELAN 1,704,370

' THERMOSTAT Filed Sept. 22, 1924 5 Sheets-Sheet 2 March 5, 1929. L. A.M. PHELAN THERMOSTAT Filed Sept. 22, 1924 5 Sheets-Sheet 3 Panta Mar.5,1929. ,s 1,704,370

UNITED STATES PATENT OFFICE'.

LOUIS A. PHELAN, OF IBELOIT, WISCONSIN, ASSIGNOR TO AB\SOLIITECON-TAC-TOR CORPORATION, OF BELOIT, WISCONSIN, A CORPORATION K015'ILLINOIS.

l x THERMOSTAT. p

Application led September 22, 1924; Serial No. 739,056.

My invention relates to automatically opment, is provided for themercury contactor, erated electric switches and more particuallowing thecontactor to be tiltably carried larly tofthose having enclosed contactsso that it is sensitive -to the slightest movewhich make and break thecircuit andl which ment by the thermostat.

are capable of handlingsubstantial quan- A further object of myIinvention is to 60 tities of current at commercial voltages.` providethe resilient supporting means for While I shall describe my inventionasl the lmercury contactor in the form of cur- =having particularapplication to` a type of rent conductors coextensive withthe leadswitchprovide with enclosed contacts, itl iii-wires whereby a`dual function isprovidwill nevertheless ybe understood that any ed: viz, that ofabsorbing the kinetic energy 65 type of switch may be used, which isautoof the movable body of mercury within the matic in operation and maybe actuated by\ contactor, which places the opposite side of anactuating force imparted by La device this supporting means undertension to provided for the purpose, notwithstanding rassist in thereturn of the contactor to its 16 that the former type of switchmay beprefnormal position, and secondly, that of carry- 70V l erable onaccount of its durability and siming the electric current to thelead-in-wires plicity of design. which eliminates the usual wiresheretofore The present invention, however, refers employed. moreparticularly to a thermostatically op- A still further object of myinvention is 20 erated switch which comprises a heat reto provide animproved form of mounting 75 sponsive element or thermostat that proforthe thermostatic or heat responsive elevides .an actuating force for theelectric ment whereby it will be thermally insulated switchingmechanism" for opening and closfrom its support, and so positioned thatthe ing the electric -circuit as the thermostat. natural flow of aircurrents will contact expands andcontracts by reason of tempera.- withits maximum surface.

. ture changes that may inliuence it. In accomplishing these and otherobjects The switch, which I employ, is preferand advantages of myinvention, Iam able I ably of the tiltable mercury contactor type toprovide an exceedingly simple and comwherein -thevco-operating contactmembers pact arrangement of the parts in a device or electrodes betweenwhich thel circuit is Which is durable, reliable and eiiicient. 85

made and broken, are fixedin position and -When controlling motorcircuits, I have are adapted to be bridged by a conducting found itunnecessary to employ relays or body, such as mercury, that is moved toand like devices,` as the switching 'mechanism fro by an actuatingthermostat at the eX- which I use has a large current carrying ca- 5pense of very little energy, such as may be pacity and is capable ofquick and accurate 9o .available when a temperature ,change of aoperation by the expenditure of very little few degrees only, or even adegree, may energy. f occur. The co-o'perating contact members In thedrawings: v of my f, switching device are spaced a suit- Figure 1 is afront elevational view of a 405able distance from one another topreclude device embodying my invention withlfthe 95 premature electricdischarges between cover'omitted so that the various operating them, andthey are completely enclosed in parts of the structure will be moreclearly a sealed container, thereby insuring them illustrated; J againstcorrosion, contamination and dcte- Fig. 2 is aside elevationalviewthereof i rioration. with the cover illustrated in section showing 100An object of my invention resides in the 4the manner of mounting thedevice upon a provision of an improved form of thermowall in thermallyinsulated relation;

- y statically operated switch of the tiltable Fig. 3 is a perspectiveview of the mercury mercury contactor type, wherein novel meanscontactor and the mounting provided thereare provided for resilientlysupporting the for; 105

mercury' contactor and for absorbing the Fig. 4 is a section taken online' 4-4of 1 kinetic energy of the movable, body of mer- Fig. 1,illustrating the means for adjusting c ury contained in the contactoruponoperathe tilting 4position of the mercury contion of the. switch. Apivotal mounting tactor.; K

which is connected `to the tliermostatic ele- Fig. 5 is a horizontalsectional view illus- 110 trating the knife blade engagement of thelaforesaid lmeans illustrated in' Fig. 4 withl ing a modified form of myinventionzwhich is provided with the thermostatic element in verticalposition; Y I

Fig. 10 is aside elevational view thereof; Fig. 11 isa front view ofanother modified form of my invention; and

Fig. 12 is a view of 'the same device looking from the rear thereof.-

The device illustrated in Fignres 1 and 2 preferably comprises amounting base 1 of bakelite, or other suitable insulationx material, towhich is secured a bracket 2 by means of screws 3 entering from the rearof the base l and having their heads seated within a recess 4 inthe rearface of this base. Bracket 2 is provided with a for.- Wardly extendingportion, 5 having a slotv 6 cut therein along 4the front edge. Athermostatic element L7 is adapted to be suption or expansion of .thebellows 7 may be i transmitted, to allow the upper end ofthe actuatingmember to readily flex for operating a mercury contactor .25, suitably-supported at the upperend of insulating base 1.

Mercury contactor 25, in this instance,

comprises. a sealed container 26, preferably a glass` tube, in whichcooperating electrodes 27 and 28 are sealed. The container ported uponinsulating base 1. Thermo-" static element 7 is of the expansible andcontractible bellows type, the interior of which may be provided with ahighly volatile fluidwhich renders the bellows sensitive to theslightest temperature change. In order that the operation of the bellowswill be eiiicient and accurateand will notfbe influenced by thetemperature of the adjacent parts ofl the device, I provide a thermallyinsulated support which prevents the cbnduction of heat to the bellows7. This thermally insulated support, as illustrated in the Figure 6,comprises a projecting shank 10 at the right-hand end ofthe bellows anda heat -insulated collar 11 adapted to' seat in slot 6 of bracket 2.Nuts 12 on each side of the collar 11 serve to hold the shank 10 seatedin the 'slot 6 of bracket 2. The left-hand side of the bellows 7terminates in a stud 13 adapted to seat in a recess 14 provided in abearingl 15. This bearing 15 ff is furnished with a point contact withone end of a screw 16 projecting from an actuating member 17.

Actuatingmember 17 is vertically positioned and is adapted to befurnished with a lleaf/spring mounting 18 at its lower end.

As illustrated injFigure'7, which is a bottom plan viewl of this leafspring mounting, the actuating member 17 is provided with a horimercury29, aswell as -an :inert gas. The container 26 is of tubular form havingits longitudinal axisplaced approximately horizontal. The electrodesor'contact members 27 and 28 are made ofpure metal and are disposed onone side of the axis of rotation of the mounting for the mercurycontactor. A tiltable mounting is provided for the mercury contactor,which allows mercury 29 to ride on a lower annular surface ofcontainer-26, and, when tilted to the left of Figure 1, it serves toestablish an electric circuit betwgen the electrodes 27 and 28. When thecontactor 25 Ais tilted in the direction illustrated in Figure 1, .themercury 29 flows tothe `other end of the conf ytainer 26 and therebyopens the electric circuit between the cooperating contact members orelectrodes 27 and 28. Electrode 27 is connected in electrical circuitthrough a leading-in-wire 30, which is embodied in the glass shank 31,thereby providing a substantial support for the leading-in wire 30.

bedded in a glass shank 33. Thus it will be seen that the electrodes 27and 28 are -23 is evacuated .and contains a body of fixed and stationarywith respect to each ing a portion 37 which is aperturedv at its lowerend as indicated at 38. An annular clamping ring 39 securely grips themercury contactor 25 at a point substantially midway of its ends. Theclamp 39 is brought tightly against the glass container 26 by means of ascrew 40 and a cooperating nut 41. One of the lower ends, desig-r nated4:2,k of clamp 39\forms a downwardly i projecting apertured extension,while the vother end 43 of said clamp 39 is adapted to have fixedthereto one end of a rod 44. The opposite end of this rod 44 is pivotedin the lower apertured end 38 of the portion 37 of bracket 34. From thedescription thus far, it will be seen that I provide` a pivotal mountingfor the mercury contactor 25, which is located substantially at a pointbetween the ends of the contactor. The arrangement reduces frietionallosses to a minimum because friction at th/e pivot point of contactor 25is practically negligible. Apertured extension 42 of clamp 89 is4adapted to connect to the rupper'end of the actuating member 17 bymeans of a rod 45. Actuating member 17 has yits upper endV 46 alsoapertured which permits rod 45 to be accurately adjusted with respect tothe actuating arm and position of the contactor 25, to compensate,f forany mechanical or manufacturing inaccuracies.

Tol provide a balanced support for the mercury contactor 25, I providemeans for resiliently supporting the contactor at its ends. In additionto accomplishing this purpose, said means further functionsto absorb thekinetic energy of the movable body of mercury 29 in the container 26when the switch is actuated. This means comprises a pair of leaf springmembers 48 and 49, best illustrated in Fig. 3. Each leaf springv isprovided with an extension 50, which is adapted to connect with theterminals 51 of the electric circuit. The leaf spring extends upwardlyand then outwardly, re sulting in forwardly projecting arms 52. The endof each arm 52 is apertured for the purpose of receiving, in fixedrelation, the projecting tips of the lead-in wires 30 and 32. The springmembers 48 'and 49 are in electrical conducting relation between thelead-in wires 30 and 32 and the terminals 51'l of the circuit. Thisarrangement elim` inates flexible leads and further eliminates theinfluence which tension in flexible leads would have on the movement ofthe contactor 24 when operated. Furthermore, these resilient memberstend to restore the contactor to normal position when tiltedirrespective of whether normal position is in closed circuit position oropen circuit position. 1

I provide means for adjusting vthe tiltable position of the contactor 25in order to obtain a proper setting or .adjustment of the bellows 7, sothat it will be adaptedto operate the contactor at a desired temperaturechange. This means comprises a hori Zontal tension spring 55 having itsaxis substantially parallel to the axis of the bellows 7 and adjustableby a knurledthumb screw 56 which is journaled in a portion 57 of bracket2. Spring 55 tends to place a tension on the actuating member 17, and,due

to the fact that its axis isparallel to that -of the bellows, thistension will be maincarried by\a second screw 58. As illustrated v inFigure 5, an aperture 59 of a diameter greater than the diameter ofscrew 58 is furnished in actuating member 17, and through this aperture59 screw 58 is adapted to project, the screw being held out of contactwith the periphery of the aperture. At the outer end, a `member 60,through which screw 58 passes, furnishes a knife blade contact betweenythe actuating member and the screw 58. The tension on t-he actuatingmember 17 may be varied by turning the knurled screw 58 in eitherdirection. It will be noted in Fig. 4 that the actuating member 17 has alateral extension 61 ex-v tendingn between spaced parallel lugs 62.Lateral extension 61 of the actuating member 17 has, therefore, limitedmovement between these spaced parallel lugss62. vWhen reaching the endof its movement, the projection 61 still' allows further tension' to beapplied to the actuating member 17. Mini-l mum frictional losses areobtained where the tension spring 55 connects to the actuating member17, and consequently, a finer adjustment of the position of contactor 25at its pivotal mounting may be obtained. An indicator plate 68 may besecured` to the portion 57 of bracket 2, as indicated at 64.y Qne end oftension spring 55 is soldered or otherwise secured to a collar 65, fromwhich a member 66 projects. An indicator arm 67 is pivoted at 68 toindicator plate/63. The upper portion of indicator arm 67 em# braces theperiphery of indicator plate 63 along which temperature calibrations areprovided for indicating the ,temperature at which the bellows'may be setto operate the switch.;

very fine and accuratetemperature setting may be obtained by having thefulcrum point of actuating arm 17 substantially at its lower end. Byhaving its point of conj \tact with the bellows substantially adjacent.

to this fulcrum, the actuating arm 17 multiplies the motion of thebellows in a large ratio, and consequently, secures operation of thecontactor 25 with a very slight motion of the bellows.v The thermallyinsulated support for the bellows secures maximum efficiency in theoperation of the latter, and the temperature of the surrounding partswill have practically no effect thereon.

In Figure 8,'I have illustrated a cover 70 adapted to be placed over thefront of the device and suitably secured to the insulating mountingbase 1. A plurality of elon gated ventilation openings 71 are providedin the cover 7 0 on the under side, and at the l45 currentsl of air thebellows presents a maxia lug 85 fixed to t e casing 87, .Bracket 84 l`mum surface. The bellows-7 1s, therefore, is guided in its movement bya screw 88 upper end of the front face, a second set and moreover, thedisposition of the bellows' recess 90 similar to the recess 4\in thelower f so that a maximum surface thereof is exposed to the air currentswithin the cover permits the device to be very sensitive to any changeof temperature in the room.

` In Figure 2, a novel form of wall mounting for the insulating base 1is illustrated. A

end is provided in the upper end of the in,- sulatingbase 1. Thermalinsulating material 91, such as felt, or the like, is adapted to beinserted inrecess 90. Attached to the wall at end of a coil spring 55,as yindicated at 80.

Actuating arm 17 then extends downwardly at 7 6 to provide a leaf springmounting 77, which is similar to the mounting 18. The upper end ofactuating arm 17 interconnects with contacter 25, which is provided witha mounting substantially the same as in the form previously prescribed.yWhile I have not shown an indicator'plate in connection with thisembodiment, it is to be understood that the same Imay be provided and`connected to the tension spring inj any suitable/manner, so that themovement ofthe knurled thumb screw 56` will adjust the tilting positionof the contactoi; 25 with respect to the bellows 7.

In Figures 11 and 12, I have illustrateda device embodying several ofthe essential features of my inventionwhich is, however,

.proper connecting-of the wiring may be )a thermostatic element.

this point is anv outlet box 92,L in AWhich operated by -a pressureelement instead of l By referring to made. Wires 93' leading from thefront side Figures 11 and 12, it Awill be noted that one of insulatingbase 1 at the terminals 50 are end of the Bourdon pressure gauge 79 isconnectedy at 94 to circuit wires 95 leading connected to a, nipple 8Oawhile the opposite upwardly through the COIldut 96- This 211'? end has arod 81 fixed thereto. A link 82 rangement serves to thermally insulatethev ispivotally connected at 83 to a bracket insulating base 1 from theoutlet box 92 84, In this device, which is usually sunk in the wall andsubject otally mounted and resiliently supported at to currents of airtherein, which currents of its ends, the same as was previously dea1 rare generally of varied temperatures and' scribed for the embodimentillustrated in dlferent from fthe room temperature, and Figures Lto 8inclusive. Link 82 connects are apt to affect the operation of asensitive with the depending arm 42 of the clamping thermostat. The padof felt 91 covers the ring .39 carrying the contacter 25. Upon lportionof the base 1 exposed to the outlet movement of the Bourdon gauge 79,the rod box 92 and preventsconduction of heat to' or 81 with itsright-angular projections 83 will from the base 1, thereby thermallyinsulatvtend to engage the under side of link 82 for ing it from alltemperature effects as the retilting the mercury switch to open andclose sult of its contact with the wall. It is there- Ythe circuit.

by impossible for the temperature controlled j In order to adjust or setthe, device to Abellows 7 to expand or contract except by operate at apredetermined pressure, aslotthe temperature effects of the currents ofted bracket 84, to which the link 82 is pivvshanksof these screws whichwould otherair circulated through the cover, to which oted, is fastenedb means of a screw 86 to sensitive and dependable, and exceedinglyriding in its slot and entering the lug 85. accurate in its operation ofthe contactor' Casing 87, however, is provided with an 25, the latterbeing capable of tilting at opening\89 into which a tool may be insertedthe slightest movement ofy` the bellows 7. for adjusting screw 86. Whenit is desired Insulating base lmay be provided with for the device tooperate at a desired presa plurality of elongated slots99 which aresure, the tilting position of contactor 25 is adapted to receive screws100 for mountingv varied, this in turn changing the position the base tothe` wall. Screws 100 pass of the arm 82 with ,respect to`the rightthrough the felt 91, but the felt serves to Langular projection 83, sothat'a greater or a cover the slots, and due to.' their elongationsmaller movement ofthe link 81 `will be re- (which permits adjustment ofthe screws) quired, it depending on the pressure at the felt prevents anopening adjacent the i-which 'the device isfto operate. l

The mercury contactor 25, which I have l disclosed herein, may be of anytype, if so wise appear.

0n-Figures 9 and 10, I have illustrated desired. However, as I havedisclosed it, it the device provided with the bellows 7 and is of thetype of contactor more particularly coil'spring 55 disposed vertically.The ac-X described and' claimed in my `copending aptuating member 17 isprovided with a lateral plication, vSerial Number 530,243, led vcontactor 25 is also piv- A' embodiments of my invention, it is to beuni derstood that many modifications may be madetherein withoutdeparting from the scope and spirit of the appended claims, and

, furthermore I desire thatonly such limita- .rtions shall be imposed asare specifically pointed out in the claims and such as are required bythe prior art.

I claim:

1. An electricswitch comprising a tiltable mercury contactor, a bracketupon which said contactor is pivotally mounted, and a spring member.having one end fixe and stationary and resiliently supporting said'contactor at an electrode lead-in wire for absorbing the kinetic energyof the movable body of mercury contained in said contactor.

2. An electric switch comprising a tiltable mercury contactor, a bracketupon which said contactor is pivotall kmounted, and leaf-spring members"having one of their ends gfixed and stationary and their other endsresiliently .supporting said contactor at the electrode leadg-in wiresfor absorbing the kinetic energyof the movable body of mercury containedin said contactor.

3. An electric switch comprising a tiltable mercury contactor, abracketr upon which fsaid contactor is pivotally Jmounted, andleaf-spring members having one of their ends xed and stationary andtheir other ends resiliently` supporting said contactor and servingL ascurrent conductors to said contactor. f Y

4. An electric switch comprising a tiltably mounted A contactor,A amounting base therefor, spring members secured at one of their ends tosaid mounting base and attached at the other of their ends-to theelectrodes of said contactor thereby permitting said contactor to betilted.

l 5. An electric switch comprising a mounting base, a mercury contactorpivotally mounted` thereupon, and spaced leaf-spring members severallyattached at one of their ends to said mounting base and secured at the`other of their ends to the electrode lead-in kwires of said contactor,said leafspring members serving'as conductors for said contactor and asshock-absorbing means for abs/orbin the kinetic energy of the `movablebody o mercury in said contactor.

6. An electric switch comprising a tiltable mercury contactor, a bracketfor pivotally mounting said contactor, and leaf-spring members disposedon both sides of said bracket and having one of ,their ends attaohed tothe electrode lead-in wires of said contactor and the other of theirends fixed and stationary.

7 An electric switch comprising a tiltable` mercury contactor, a memberupon which said contactor is pivotally mounted, and resilient meansdisposed on each side of said mounting member and having `one of theirends connected to the electrode lead-in wires of said contactor and theother of their ends fixed and stationary, lsaid resilient means servingas current conductors and as shck-absorbingmeans for said contactor.

8; Anelectric switch comprising a tiltable mercury contactor, a bracketfor pivotally mounting said contactor adjacent to its center, andleaf-spring members vdisposed on both sides of said bracket and havingone' of their ends engaging said contactor adjacent to its ends and theother ends of said leaf-spring members being `fixed and stationary.

9. An electric switch comprising a pivotally mounted mercury contactor,and L- shaped leaf-spring members resiliently supporting said contactorupon its pivotal mounting and serving as current conductors to theelectrodes of said contactor, said 11. An electric switch comprisingamount- .ing base, a bracket, a mercury contactor pivotally mounted onsaid bracket, space d leaf-spring members having one of the1r endsconnected to the electrodes of said contactor and the other of theirends secured to said base member for resiliently supporting said mercurycontactor, means for adjusting the tiltable position of said contactor,and eXpansible and contractible means for tilting said contactor uponsaid bracket.

12. An electric switch comprising a mounting base, and a mercurycontactor pivotally mounted thereupon, resilient supporting mea'ns forbalancing said contactor about its pivoted mounting and serving ascurrent-conductors to said contactor, and expansible and contractiblemeans for tilting said contactor about its pivot, said resilientsupporting means being stationary and fixed sto said mounting base andserving to absorb the kineticv energy of the movable body of mercurycontained in said contactor.

13. 'An electric switch comprising a mounting base, a mercury contactorpivoted thereupon, L-shaped. leaf-spring members and balancing saidcontactor about Said supporting said contactor about its pivot at n itsleading-in wires upon one of their ends,

electric terminals connected to the other ends of said leaf-springmembers, and means for tilting said contactor Jabout its pivotalmounting, said leaf-spring members being stationary and supported uponsaid mounting base and serving to absorb. the kinetic energy of themovable bodyof mercury contained in said contactor.

14. An electric switch comprising a mounting base, .a mercury contactor,a pivotal mounting ,for said contactor, L-shaped leaf-spring members.supporting said contactor at its leading-in wires upon one of theirends `and balancing said contactor upon y said pivotal mounting,electric terminals connected tol the other ends of said leafspringmembers,.means for tilting said contactor about its pivotal mounting,said leafenergy of the movable body of mercury contained in saidcontactor, and means for varying the position of said contactor aboutits pivot.

15. An` electric switch comprising a mounting base,` a mercurycontactor, a

pivotal mounting for' said contactor, L*-

shaped leaf-spring members supporting said contactor uponone of theirends7 to balance said contactor upon said pivotal mounting and the otherends of said leaf-spring members being secured to said mounting base,rheat responsive means for tilting said contactor about its pivtolmounting, said leafspring members serving to absorb the kinetic energyof the movable body of mercury contained in said contactor, and meansfor varying the position of said contactor about its pivot.

` 16. A balanced mounting for a mercury contactor having a centrallylocated pivot comprising a clamping member' secured at a substantiallycentral point on said contactor, a bracket for carrying said 'clampingmember, and resilient members adapted to be attached to the ends ofvsaid contactor and tending to return the contactor to normal positionwhen tilted.

17. A balanced mounting for a mercury contactor comprising meansproviding d,a centrally located pivot for the contactor,v in combinationwith resilient members connected directly to the leading-in Wires," ofysaid contactor adjacent to both of itsends and tending to balance thecontactor about said pivot while tilted, said resilient members servingas current conductors to said leading-in wires. f

18. An electric switchicomprising a pivotally mounted mercury contactor,a base for Said pivotal mounting, resilient means con-V pivotalmounting, said resilient means being attached to said base, a thernallyinsulate lheat responsive device on said base, and in- 1 n a saidplvotal mounting, reslllent means connected adjacent to the ends of saidcontactor land balancing said contactor about said pivotalmounting, saidresilient means beingv attached to said base, a heat responsive meansfor actuating said contactor, means for horizontally mounting said heatresponsive device on said base in thermally in sulated relation, andmeansfor interconnecting said contactorand said heat responsive device,said resilient means serving asi Vcurrent conductors to electrodes inj/said contactor. l'

20. electric switch comprisingY a tiltable mercury contactor, a pivotalmounting therefor, a base for said pivotal mounting,

resilient electrical conductors connected to` base, a heat responsivedevice for actuating said, contactor, means for horizontally mountingsaid heat responsive device on said base in thermally insulatedrelation, a vertical actuating arm having its fulcrum in close proximityto the point of contact with said heat responsive device for multiplying'the movement of said heat responsive device, and adjustable meansinterconnecting said actuating arm with said contactor for transmittingthereto the adjustably multiplied movement of said heat responsivedevice.

21. AnA electric switch comprising a tiltable mercur contactor, 1apivotal mounting therefor, a ase for said pivotal mounting,

resilient electrical conductors connected to thelleading-in wires ofsaid contactor adja- 4centto. the ends thereof, said electrical con--ductorsY tending to balance said contactor' about said pivotal mounting,and having their corresponding ends attachgd to saidj base, a heatresponsive device on said base for actuating said contactor, anactuating arm for transmitting the movement of said heat responsivedevice to said mercury contactor, said actuating arm being disposed atlright angles to the axesofsaid contactor and said heat responsivedev1ce, and"adjust i ablemeans for varying the degree of movement ofsaid contactor in response to said heat responsive means. f I

.22. An electric switch comprising a tiltable mercury contactor, apivotal mounting therefor, a base for said pivotal mounting,

tactor, a heat responsive device mounted on said base, an actuating arminterconnecting said' contactor and heat responsive device fortransmitting the motion of the latter toithe former, said actuating armbeing mounted for, movement substantially in the same direction ofmovement as `said heat responsive device, and adjustable means'forvarying the degree of movement of said contactor in response to saidheat responsive means. l

' 23. An electric switch comprising a tiltrable mercury contactor, apivotal mounting therefor, a base for said pivotalmounting, resilientelectrical conductors connected to the leading-in wires of saidcontactor adjacent to the' ends thereof, said electrical conductorstending to balance said contactor,1

about said vpivotal mounting and having their corresponding endsattached to said base, a heat responsive device mounted on said basein,l thermally insulated relation, an actuating arm for transmitting themotion of said heat responsive device to said contactor, said thermallyinsulated mounting comprising a bracket, a shank 'at one end of saidheat responsivedevi'ce adapted to seat in said bracket, thermalinsulating material between said shank and said bracket, and a singlesharp point contact between the opposite end of said heat responsivedevice and said actuating arm whereby the heat` flow between said armand said heat responsive device will be minimized.

24. An electric switch comprising a tiltable mercury contactor, amounting base therefor, Ya heat responsive device mount; ed on said basein thermally insulated relation, an actuating arm fortransmitting themotion of said heat res onsive device to said contactor, said thermal. yinsulated mounting comprising a bracket, a shank at one end of said heatresponsive device adapted to seat in said bracket thermal insulatingmaterial between said-shank 'and said bracket, single point contactmember aflixed to the opposite end of said heat responsive device andengaging said actuating arm, and means including an adjusting screwcarried by said actuating arm for engaging said single point contactmember.

v25. An electric switch comprising a tiltable mercury contactor throughwhich an external electric circuit is controlled, a

mounting base for said contactor, an expansible and contractible-bellowsserving as a heat responsive device for actuating said contactor, anactuating armv engageable by the movable end of said bellows fortransmitting the motion of said bellows to said contactor, and anadjustable element interfposed between said actuating arm and themovable end of said bellows for permitting initial calibration of thelatter when mount- -ed on said base. i

26. An electric switchl comprising a tiltable mercury contactor throughwhich an 'external electric circuit is controlled, a

mounting base for said contactor, an eXpanvsible andicontractiblebellows serving as a heat responsive device for actuating saidcontactor,van actuating arm enga eableby the movable end of said'bellowsor transmitting the motion of said bellows to said contactor, and anadjustable element interposed between said actuating arm andjthe movableend of said bellows for permitting initial calibration of the latterwhen mounted on said base, said element providing a point contact forthe movable end of said bellows for minimizing friction and heatconduction thereat.

27. An electric Aswitch comprising a tiltable mercury contactor,amounting base therefor, an expansible and contractible elementhorizontallydisposed thereon, an actuating arm for connecting saidcontactor and .said element in operative relation, a casing housing .theaforesaid elements, and means for varying the tilting position of saidcontactor whereby said element may be adjusted so that its movement tooperate said contactor maj be predetermined, said means acting paral elto the aXis of said element and being exteriorlyaccessible of saidcasing.

28. An electric switch comprising a tiltable mercury contactor, amounting base therefor, an expansible and contractible elementhorizontally disposed thereon, an actuating arm for connecting saidcontactor and said element inoperative relation, a tension spring actingin a direction parallel to .the laxis of saidf element for varying thetilting position of said contactor, a casing housing theaforesaideleinents, and means eXteriorly accessible of said casingforadjusting saidj tension spring.

l 29. An electric switch comprising a tiltable mercury contactor, amounting base therefor, an expansible and contractible elehment disposedthereon,y an actuating arm adapted toconnect said contactor and saidelement in operative relation and spring means associated with saidactuating arm at .s

a point intermediate said contactor and ,element for varying thetilting'position of said contactor, said spring means includingYatension spring provided with a. knife blade engageinent with -saidactuating arm and an adjusting means for varying the tension of saidspring against said actuating arm.

30.y An electric switch comprisingamounting base, a heat responsivebellows v'located at the lowermost. portion thereof and having its axisplaced horizontally, a vertically'arranged lever pivotally mountedadjacent. to said bellows and extending upwardly there'- from, atiltable electric contactor pivotally vmounted adjacent to the upper endofsid leverand near'the upper portion of said mounting base, and meansfor connecting i .saldf lever and said contactor whereby movements ofthe said bellows maybe imparted to tilt said contactor, said contactorcomprisin a container, electrodes sealed therein and a of mercuryadapted to control an external electric circuit through said elec'-Vtrodes when said contactoris tilted.

, 31. An electric switch comprisingamountingf base, a horizontallydisposed heat Yresponsive yelement located at the lowermost portionthereof, an electric tiltable contactor .located on said base above saidheat responsive element, means for connecting said contactor and saidelement in operative relation, and a container for said heat responsiveelement having vents therein whereby the maximum surface of heatresponsive elements is presented `to the natural flow of air currentsthat influence said heat/responsive elements,` said contactor comprisinga container, electrodes sealed therein and a body of mercury adapted tocontrol an external electric circuit through saidelectrodes when saidcontactor is tilted.

32. An electric switch comprising a tiltable mercury contactor, amounting base therefor; a'fbellows element located at the .lowerportion-of said base and having its for said contactor` including anapertured'depending arm, an expansible and contractible ellows servingas a heat responsive device, an actuating arm between said contactor andsaid bellows, the end of said actuating arm adjacent to' said contactor'having lone or; more apertures provided therein, and an interconnectingmember between the apertured end ofsaid actuating arm and said aperturedpyro-1,979 I depending arm permitting accurate adjustment of the partstol compensate for inaccuracies in the manufacture thereof.

'341. An electric switch comprising a tiltable mercury contactor, amounting ,base

therefor, means for pivoting said contactor upon said base, andresllient conductors havmg one of their ends attached to said base andtheir other ends lattached to the leading-r "in'wires" of said contactoratthe end'por-tions thereof for balancing said contactor upon itspivoting means.

35. An electric switch comprising a tiltable contactor, a mounting base,pivotal` means engaging said contactor intermediate its ends, and springmembers constituting leading-in-wires for said contactor and beingconnected to the end portions of said contact-or for balancing the sameupon its pivotal means.,

36. An electric switch-.comprising a co-ntactor, a mounting basetherefor, means for pivoting said contactor adjacent to its center 4upon said base, spring means vconstituting leading-in wires to Isaidcqntactor for balancing said contactor vin normal position upon itspivoting means, and actuating 'means for tilting said contactor in\opposition tothe force exerted thereupon bysaid spring means.

37. An electric switch comprising a contactor, a mounting base therefor,means for pivoting said K contactor upon said base,

spring means constitutingleading-in wires to said contactor forbalancing said contactor in normal position upon. its pivoting means,and heat responsivepmeans for tilting saidrontactor upon its pivotingmeans in opposition to said spring means.

38. An electric switch comprising a tiltable mercury contactor, amounting base therefor, resilient supporting means providing ycurrentconductors for said contactor, and a pressure element fortilting saidcontactor about its pivot, said resilient supporting means serving toabsorb the-kinetic energy of the movable body of 'mercury contained insaid contactor.

39. An electrictswitch comprising a tilt;

\. able mercury contactor, resilient supporting means for said contactoradapted to servel as current conductors therefor and tending to minimizethe energy required Ato vtilt said contactor as well asbalance the samewhen tilted, a pressure element for tilting said-con- A tactor about itspivotvfor opening and closing the circuit, and an adjustable connectionbetween said contactor and said pressure element for predetermining theeffectiveoperating pressure of said pressure element.

In witness whereof, I have hereunto Vsubscribed my name. 4

' LOUIS A. M. PI-IELAN.

